When I tested out various desktop search tools Google Desktop search looked pretty feeble. I use Yahoo's relabeled X1 product -- it's not perfect but it's pretty acceptable on reasonably modern hardware.
But now Google has laid down another card - GDS plugins that extend its functionality:
This plugin is a web spider ('Kongulo' is Icelandic for spider) that crawls websites you specify and makes them searchable via GDS.Note my emphasis. This is a personal version of a corporate indexing tool. I'd guess it wouldn't scale to a large corporation, but who knows? In the meantime I'd use it to index my blogs so I can find stuff in them.
Kongulo follows links in HTML frame, image and anchor tags. It obeys robots.txt and knows basic and digest HTTP authentication. It can be run continuously, checking for updates to previously crawled pages, and uses the If-Modified-Since HTTP header to minimize transfers when doing so.
You can provide a regexp to limit crawls to e.g. your intranet domain.
This version does not have a graphical user interface and can be run from the command-line only.
The product itself is interesting, but it emphasizes two things:
1. GDS might have a future.
2. When you build a product around Plugins, you gain a lot of power.